Sound

Imagine a world without any sound, we could not listen to our favourite music, or hear birds chirp in the morning. On the bright side, it meant that the sound of thunder would not frighten us during a storm, but then we would not be able to hear news of impending danger on the radio.

What is Sound?

They are 4 main properties of a sound wave, wavelength, amplitude, period and frequency.

Wavelength and Period

If we compare a sound wave with the ones we see at the beach then a wavelength can be defined as the distance between two consecutive wave peaks. The period of a wave is the time it takes it to pass through a particular point. Therefore the period is the amount of time it takes to travel one wavelength.

Amplitude

Thinking of those waves at the beach again, we can think of the amplitude as how high the wave is. The bigger the wave is the louder the sound it makes when it crashes onto the sand. We say that this wave has high amplitude. Therefore waves with high amplitude create louder songs and vice versa, waves with small amplitude create soft sounds.

Frequency

The number of waves, which pass through a particular point for unit time (e.g. during a second) defines the frequency. The frequency of a sound wave is measured in Hertz (Hz).

Pitch

Pitch is determined by how the brain interprets the frequency of an emitted sound. The higher the frequency the higher the pitch and the higher is the sound that is interpreted by the air and vice versa the lower the pitch the lower the sound heard.

The Speed of Sound

The speed at which sound moves depends upon the medium (material) it is passing through. Sound waves travel the slowest through gases and fastest through solids. Temperature also affects the speed at which sound waves move.

At freezing (0º Celsius), sound travels through air at 331 meters per second (about 740 mph). But, at 20ºC, room temperature, sound travels at 343 meters per second (767 mph). In fresh water, sound waves travel at 1,482 meters per second (about 3,315 mph), a great deal faster than it does in air. Several ocean-dwelling animals such as whales and dolphins use sounds to communicate with one another and find food. This method of communication is effective because sound waves travel much faster through water. Sound moves fastest through solids, it can move through steel at 5,960 meters per second (13,332 mph). However, the speed of sound in all solids is not faster than in all liquids.